Hi Charles,
There are a few ways this can be done
Have a look in CUCM under Call Routing> Directory number and you can set it up there.
You can have a DID/DN with Call Forward set up without an actual phone by doing it via this config.
You can also use Device > CTI Route Point as the same "virtual" config can be set there as well.
Set the CFWDALL on the DN page of the CTI-RP.
I prefer the CTI - Route Point method as you can search for it easily and it won't be deleted
by accident.
Cheers!
Rob
"Why not help one another on the way" - Bob Marley